The present invention is concerned with dental hand pieces, it being an object to provide a collet arrangement fitting in a dental burr tube with means affected by centrifugal force to seal off workable parts of the handpiece from substances which the handpiece comes into contact with, such as abrasives, ground tooth matter, particulate food matter, saliva and bacteria. In the prior art, problems have existed with such matter entering dental handpieces and causing wear and tear, corrosion, and the breeding of bacteria within handpieces. Working parts within handpieces are especially affected when such debris contacts them.
A specific object is an engaging member for a dental tool having a flexible flange or skirt means engageable in a counterbore of a handpiece head wherein it may seal by centrifugal force, and which is independent from the tool.
A further object is to provide an engaging member for a dental tool with such a flexible flange seal that does not subject the sealing means to thrust forces in use.
In the prior art, devices used to block pumice such as that shown in U.S. Pat. No. 3,407,502 to G. E. Richmond there is an annular bead 79 on a cap 60 which fits into a groove 78 in a hub 68 for the purpose of blocking pumice. However these parts being of metal do not provide a centrifugal force seal.
Other dental handpieces are shown in Richmond U.S. Pat. Nos. 3,436,830, Bailey 4,014,099, and Fernald 1,170,523 and Etherington 3,978,586 and the art cited in them. Cooper 2,469,261 purports to illustrate an arrangement by which a rubber cup can seal by compression, but it is noted that, among other things, the driving mechanism between the shaft and the rubber cup is part of the same mechanism that is supposed to give the sealing arrangement. Another part of the Cooper sealing arrangement is part of the dental tool used.
The present invention improves over the prior art. The collet is of plastic and molded in one piece. The skirt of the collet is resilient, and the remainder of the collet can also be resilient or can be of metal. The sealing means, that is the skirt, is a part of the collet and is not attached to the dental tool such as a dental burr. This means that a single skirted collet can be used with several different tools of the same or different type. Having one skirt on the collet thus is much more economical than having a sealing means provided for each tool.
The collet, being molded of one piece, can be readily replaced for repairs by another such collet. The collet preferably has a body with a closed end which prevents passage of debris through the collet into the burr tube and towards the working parts of the handpiece. With the present device, it is unnecessary to use a screw to hold the tool in the collet because of the collet friction grip.
In a modification, the skirt tapers from its hub connection to narrower width at the skirt end, which allows greater movement of the skirt end by centrifugal force.
Another modification has an outwardly slanting skirt that contacts the surface of the counterbore when the skirt is stationary.
In another modification an extractor pin is provided for removal of a dental tool from a collet in a modified head. The interior end of the collet has a pin receiving bore, and the modified head has bores through its cap, driven gear and burr tube that are aligned with the collet pin bore for receipt of the pin shaft so that the pin can push the dental tool out of the collet. One form of the pin has a flat head with a neck to space the head away from the handpiece cap to provide for insertion of a fingernail or other thin object to pry the pin. Another form of the extractor pin has a looped end for insertion of a finger to push and pull on the pin shaft.